▎ 摘　　要

The distribution of Co in pristine and nitrogen-doped graphene is investigated. The coexistence of Co nanoparticles and Co2+ ions is formed by the deposition process. The distribution of Co can be tuned by nitrogen doping. Raman spectra reveal the presence of different defect types in samples. This result confirms that the surface state can be modified by nitrogen doping. Annealing process demonstrates that nitrogen doping favors a stable Co2+ ion-C network, which supports the geometric stability for the Co-graphene system. Therefore, nitrogen doping can offer an effective method to realize the TM-graphene system, which has potential applications in spintronic devices. (C) 2015 Elsevier B.V. All rights reserved.